The CNHL Long Range Series BAK 50D 5000mAh 21700 Li-ion battery cell is designed for custom high-energy battery packs that need a strong balance between stored energy and usable power capability. With a 5000mAh rated capacity, 3.6V nominal voltage and 18Wh rated energy, the INR2170-50D is well suited to long-range FPV, fixed-wing RC aircraft and UAV battery projects where endurance matters but the system still requires meaningful current headroom.
Compared with energy-first 21700 cells designed primarily around maximum capacity, the 50D follows a more balanced performance direction. This makes it a strong building block for 1P, 2P and 3P Li-ion battery architectures where pack designers need to consider both flight time and propulsion demand.
This product is an individual cylindrical Li-ion cell rather than a complete ready-to-use RC battery pack. Cell matching, electrical connections, insulation, pack construction, charging and protection should be handled by users with appropriate Li-ion battery-building knowledge and equipment.
Quick Fit & Application Check
| Cell Format |
21700 cylindrical Li-ion cell |
| Cell Model |
BAK INR2170-50D |
| Rated Capacity |
5000mAh |
| Nominal Voltage |
3.6V |
| Rated Energy |
18Wh |
| Performance Direction |
Power + Energy Balance |
| Primary Applications |
Custom long-range FPV, RC airplane and UAV Li-ion battery packs |
Product Specifications
| SKU |
LI500101S70 |
| Brand / Series |
CNHL Long Range Series |
| Cell Manufacturer / Model |
BAK INR2170-50D |
| Chemistry |
Rechargeable Li-ion |
| Cell Format |
21700 |
| Rated Capacity |
5000mAh |
| Typical Capacity |
5050mAh |
| Nominal Voltage |
3.6V |
| Rated Energy |
18.00Wh |
| Typical Energy |
18.18Wh |
| Maximum Charge Voltage |
4.20V |
| Standard Charge Current |
2.5A (0.5C) |
| Maximum Charge Current |
15A (3C, not intended as the standard cycling charge rate) |
| Standard Discharge Current |
1A (0.2C) |
| Maximum Discharge Current |
Up to 5C without temperature cutoff; up to 8C under the specified 70°C temperature-cutoff condition |
| AC Internal Resistance |
≤5mΩ at 1kHz |
| Approx. Size |
Approx. 21mm diameter × 70mm length |
| Specification Envelope |
Diameter ≤21.45mm; length ≤70.75mm |
| Approx. Actual Weight |
Approx. 66g |
Power + Energy Balance for Long-Range Battery Packs
The BAK 50D is positioned within the CNHL 21700 range as the Power + Energy Balance cell. Its 5000mAh capacity provides substantial stored energy, while its electrical characteristics make it a more natural starting point than an energy-first cell when the finished aircraft must also handle meaningful takeoff, climbing or maneuvering loads.
This balance is particularly valuable in long-range aircraft. A battery may spend much of a mission at efficient cruise power while still needing additional current headroom during launch, climb, acceleration or wind correction.
The correct finished pack should always be designed around the current capability of the cell, the number of cells in parallel, interconnect resistance, wire size, connector, cooling and the actual load of the aircraft.
5000mAh Capacity and 18Wh Energy per Cell
Each 50D cell is rated at 5000mAh and 18Wh. For custom battery builders, watt-hours are especially important because Wh describes stored energy more directly than capacity alone when comparing packs with different series counts.
Using the same 5000mAh cell in series increases battery voltage and total watt-hours while capacity in mAh remains 5000mAh. Adding cells in parallel increases both pack capacity and the number of cells sharing the electrical load.
This makes the 50D suitable as a building block for a wide range of 21700 battery architectures rather than being limited to one finished pack size.
1P, 2P and 3P Battery Pack Possibilities
| Parallel Configuration |
Nominal Capacity |
General Pack Direction |
| 1P |
5000mAh |
Compact and weight-conscious long-range builds |
| 2P |
10000mAh |
Extended-range aircraft with greater energy and parallel load sharing |
| 3P |
15000mAh |
Large UAV and fixed-wing endurance systems |
The practical capability of a finished pack is not determined by cell count alone. Pack construction, cell matching, interconnect design, thermal management, wire gauge and connector selection all influence real-world performance.
21700 Cell for Long-Range FPV Battery Projects
The 50D is particularly relevant to custom long-range FPV Li-ion battery packs where pilots need more energy than a typical high-power-focused battery design while still maintaining enough usable current capability for hover, climbing and maneuvering.
For finished CNHL Li-ion products built around long-range applications, browse the Li-ion long range FPV battery collection.
21700 Cell for RC Airplane and Fixed-Wing Battery Packs
Efficient fixed-wing aircraft can make effective use of cylindrical Li-ion cells because normal cruise power may be considerably lower than launch, takeoff or climb demand. The 50D's balance of energy and usable power makes it a practical cell direction for custom FPV wing, glider, utility aircraft and endurance-oriented fixed-wing battery projects.
Finished fixed-wing Li-ion options can be compared in the CNHL Li-ion batteries for RC airplanes collection.
21700 Cell for UAV Battery Projects
Mapping, inspection, surveying and other endurance-oriented UAV systems can also benefit from 21700 Li-ion battery architectures when mission energy and aircraft efficiency are higher priorities than extreme burst power.
For assembled endurance-oriented products, explore the CNHL Li-ion UAV battery range.
BAK 50D vs Higher-Capacity Energy-First 21700 Cells
A higher-capacity 21700 cell is not automatically the better choice for every aircraft. The BAK 50D is intended to provide a stronger balance between energy storage and usable current capability, making it especially relevant when the battery must support both efficient cruising and meaningful higher-load operation.
Energy-first cells can provide more stored capacity per cell, but they may require closer current matching. For aircraft with greater takeoff, climb or acceleration demand, the 50D can provide a more appropriate starting point even when its marked capacity is lower.
Browse all CNHL 21700 Li-ion cells to compare cell platforms for custom pack projects.
Part of the CNHL Long Range Series
The 50D is part of the CNHL Long Range Series, an endurance-oriented product family built around cylindrical Li-ion battery technology for FPV, RC airplane and UAV applications.
For the complete chemistry and cell-format range, browse CNHL Li-ion batteries or explore all 21700 Li-ion batteries and battery packs.
Charging and Cell Safety
Charge the cell only with equipment and settings appropriate for rechargeable Li-ion chemistry. The BAK 50D uses a maximum charge voltage of 4.20V per cell. Standard charging is 2.5A, while higher charging rates should only be used within the official cell specification and with appropriate temperature and pack monitoring.
Do not short-circuit, crush, puncture, reverse-polarize, overcharge, over-discharge or expose the cell to excessive heat. Individual cylindrical cells should be mechanically protected from damage and should not be carried or stored loose where conductive objects can bridge the terminals.
Building multi-cell lithium battery packs requires correct cell matching, electrical insulation, reliable interconnections and appropriate charging and protection practices. This individual cell is intended for users familiar with safe Li-ion battery handling and pack construction.
FAQ: CNHL BAK 50D 5000mAh 21700 Cell
What battery cell is used in this product?
This product uses the BAK INR2170-50D cylindrical 21700 Li-ion cell with a rated capacity of 5000mAh and nominal voltage of 3.6V.
What is the energy of one BAK 50D cell?
The rated energy is 18.00Wh per cell, with a typical energy specification of approximately 18.18Wh.
How much does the CNHL 50D 21700 cell weigh?
The photographed production sample weighs approximately 66g. Small production variation can occur between individual cells.
What are the dimensions of the 21700 cell?
The cell is approximately 21mm in diameter and 70mm long. The technical specification envelope allows up to approximately 21.45mm diameter and 70.75mm length.
Is the BAK 50D a high-capacity or high-power 21700 cell?
The 50D is best positioned as a power-and-energy-balanced 21700 cell. Its 5000mAh capacity provides substantial stored energy while also offering more usable current headroom than an energy-first design optimized primarily for maximum capacity.
Can I use this 21700 cell for a long-range FPV battery?
Yes, the 50D is a strong cell direction for custom long-range FPV battery projects when the finished pack configuration can safely support the aircraft's hover, cruise, climb and peak current requirements.
Can the 50D be used to build 4S or 6S battery packs?
Yes. Multiple cells can be configured into different series and parallel architectures by experienced battery builders. For example, CNHL uses the 50D platform in 4S and 6S Long Range battery designs with 1P, 2P and selected 3P configurations.
Is this a complete RC battery pack?
No. This product is one individual 21700 cylindrical Li-ion cell. It does not by itself provide a complete multi-cell RC battery pack, main power connector, balance connector or finished pack assembly.
What is the maximum charge voltage?
The maximum charge voltage is 4.20V per cell. Always use a charger and charging process appropriate for Li-ion chemistry and the complete battery configuration.
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